1. Field of the Invention
The present invention generally relates to an electric connector for electrically connecting a flexible ribbon cable, or a so-called flat cable, having a plurality of bundled parallel cable lines, with a corresponding number of terminal elements in a generally plug-in fashion.
2. Description of the Prior Art
A flexible ribbon cable is known having a plurality of electric lead lines laid parallel to each other and bundled together into a generally ribbon-like configuration. Recent years have seen an increasing use of the ribbon cables in electric apparatuses and appliances. For end-to-end connection between one ribbon cable and the other ribbon cable, or for end-to-terminal connection between a ribbon cable and a terminal structure having a corresponding number of terminal elements, a generally flat connector is employed, having a row of juxtaposed contact elements with which cable lines of the ribbon cable are electrically connected by insertion of the ribbon cable into the connector. With the cable lines inserted into the connector so as to engage the corresponding contact elements, the ribbon cable is locked in position relative to the connector by means of a lock-on insert.
Some of the prior art connectors of the type referred to above will now be discussed in detail with particular reference to FIGS. 9 to 11, respectively.
Referring first to FIG. 9 showing the prior art ribbon cable connector in a partially sectioned, schematic perspective representation, the ribbon cable connector shown therein is disclosed in the Japanese Laid-open Utility Model Application No. 3-8886 published Jan. 28, 1991. This prior art connector comprises a plastic molded housing 1 of a generally rectangular configuration having top and bottom walls and a pair of side walls and also having a generally rectangular sectioned hollow 1b defined therein so as to extend across the depth of the housing 1 as measured in a direction parallel to the direction X of insertion of the ribbon cable (not shown). This hollow 1b is delimited by top and bottom interior surfaces and a pair of side surfaces. The top wall of the housing 1 has a plurality of juxtaposed terminal members 4 in side-by-side and equally spaced fashion in a direction widthwise of the housing 1.
Each of the terminal members 4 is of a configuration generally similar to the shape of a figure "4" including a contact finger 4a and an anchoring finger 4b, a bridge 4d connecting the contact and anchoring fingers 4a and 4b together and a connecting finger 4c extending outwardly in a direction counter to and in alignment with the contact finger 4b. The contact finger 4a is bent relative to the bridge 4d so as to approach the anchoring finger 4b. A free end of the anchoring finger 4b is so shaped as to represent a hook.
The top wall of the housing 1 has, for each terminal member 4, a slit 3 defined therein so as to extend from the rear and inwardly of the top wall 1a in a direction parallel to the direction of insertion X leaving a partition wall as indicated by 1a between it and the hollow 1b for receiving the anchoring finger 4b of the associated terminal member 4. On the other hand, the bottom wall of the housing 1 is formed with grooves 2 equal in number to the number of the terminal members 4, each of said grooves 2 opening into the hollow 1b so that, when the terminal members 4 are press-fitted into the housing 1 with the contact and anchoring fingers 4a and 4b guided along and into the grooves 2 and the slits 3, respectively, contact protuberances integral with the respective contact fingers 4a are exposed into the hollow 1b while protruding therein.
A flexible ribbon cable (not shown) is forcibly inserted into the hollow 1b to allow cable lines forming the flexible ribbon cable to be electrically connected with the respective contact protuberances of the contact fingers 4a and is then retained in a position trapped within the hollow 1b.
The prior art connector of the above described construction is generally considered as having a relatively small thickness T, for example, 2.5 mm, but the necessity of the slots 3 for the anchoring fingers 4b in addition to the grooves 2 for the contact fingers 4a, makes it difficult to manufacture a molding die used to make the housing 1. Even if it is possible to form slender molding pins necessary to form the anchoring slots 3, some of the slender molding pins may be bent or broken under the influence of a pressure of molten plastic during the molding. Therefore, the prior art connector has a problem in that not only is it difficult to form the anchoring slots 3 in the housing precisely, but the productivity tends to be adversely affected.
In addition, the presence of the partition wall 1a necessarily increases the spacing S between the contact fingers 4a and the anchoring fingers 4b and, hence, the thickness T, resulting in an increased size of the connector as a whole.
The Japanese Laid-open Utility Model Publication No. 60-188488 published Dec. 13, 1985, discloses another prior art connector for a flexible ribbon cable as shown in FIG. 10. The connector shown therein comprises a housing 1 having a terminal chamber 1c defined therein so as to open in one direction conforming to the direction of insertion X, and a plurality of juxtaposed resilient terminal members 4, one for each terminal chamber 1c. Each terminal member 4 is generally of a shape similar to the shape of a figure "S" and is so shaped and so configured as to have a generally U-shaped contact finger 4e having a gap 4f defined therein for receiving the flexible ribbon cable C and a lead-out finger, said contact finger 4e and said lead-out finger 4g being continuous to each other so as to depict the shape of a figure "S".
The connector shown in FIG. 10 also comprises a lock-on insert 5 of generally T-shaped cross-section including a generally rectangular closure 5a having a slit 5b defined therein in a direction parallel to a row of the terminal members 4, and a wedge-like member 5c perpendicular to the closure 5a and adapted to be inserted into the terminal chamber 1c. The slit 5b in the closure 5a of the lock-on insert 5 is adapted to pass the flexible ribbon cable S therethrough into the terminal chamber 1c.
To connect the cable lines electrically with the associated terminal members 4, particularly the contact fingers 4e, the lock-on insert 5 is mounted in the housing 1 with the wedge-like member 5c inserted generally halfway into the terminal chamber 1c as shown in FIG. 10 and, at this time, the lock-on insert 5 is retained in position by a resilient force exerted by the lead-out finger 4g and urging the wedge-like member 5c against the bottom wall of the housing 1. The flexible ribbon cable C is subsequently inserted through the slit 5b in the lock-on insert 5 and then into the terminal chamber 1c so as to be received within the gap 4f in the contact finger 4e. Thereafter, the lock-on insert 5a is completely inserted to allow the resilient force exerted by the contact and lead-out fingers 4e and 4g to be centered on the contact finger 4e to clamp the flexible ribbon cable C firmly.
According to the prior art connector shown in FIG. 10, since the slit 5b for the passage of the flexible ribbon cable C therethrough is very narrow, making it difficult to insert the flexible ribbon cable C therethrough into the terminal chamber 1c.
To avoid the difficulty encountered with the prior art connector shown in FIG. 10, the Japanese Laid-open Utility Model Publication No. 64-9377 published Jan. 19, 1989, suggests another connector which comprises a loose mounting of the lock-on insert on the housing as shown in FIG. 11 to broaden the mouth through which the flat cable C is inserted. Referring now to FIG. 1, the lock-on insert 5 is hingedly coupled with the housing 1 at a front end thereof when the lock-on insert 5 is in an inoperative position as shown therein, but can be slid towards the completely inserted position when, after the flat cable C has been inserted into the hollow 1b, the lock-on insert 5 is pushed.
However, with the connector of the type disclosed in FIG. 11, it may often occur that, depending on the environment in which the connector is used, no space may be available for accommodating the pivotal movement of the lock-on insert.